Design and implementation of model-assisted reduced-order ADRC for power system load frequency control problem with communication delay.

This paper addresses the load frequency control problem subjected to communication delays, actuator non-linearity, and parameter uncertainties using a Model Assisted Reduced-order ADRC (MRADRC). The approach makes use of minimal plant knowledge in the Extended State Observer (ESO) design with reduced-order so that the observer becomes delay aware, thereby improving its estimation accuracy. A two-stage tuning approach is introduced to tune the parameters of the controller. In the first stage, the Walrus multi-objective optimizer obtains a set of Pareto-optimal solutions found by minimizing frequency deviation metric (IAE) and control signal variation (TV) subjected to mixed robustness level 2≤ϵ≤5. In the second stage, multi-criteria decision-making based ranking methodology is used to obtain final optimal controller and observer bandwidths. The proposed method is implemented on two numerical studies. Study 1 focuses on the implementation of the proposed method on single-area LFC (non-reheat, reheat, hydro) plants under four different scenarios involving nominal, perturbed, and non-linearity cases. In Study 2, a more reliable benchmark system, IEEE 39-bus New England system, is considered with the controller tested for cases involving random load and variable delays. In both studies, it was observed that MRADRC exhibits considerable improvements in reducing frequency deviations and its peak level compared with PID/FOPID/PI/H∞ methods, while maintaining robustness level (ϵ) at the desired level and achieving a good delay margin.